First, a crash course on what nitrate is. Nitrogen is a chemical element necessary for living things to survive and grow. Nitrate (NO3) is one of the nitrogen compounds that is used by animals and plants as a source of nitrogen (nitrite is another — NO2).
"Nitrates differ from nitrites in their chemical makeup, with nitrates containing three oxygen compounds and nitrites containing only two," explains registered dietician Kristin Gillespie, M.S., R.D., L.D., CNSC. "Nitrates are stable and unlikely to cause bodily harm; however, bacteria and enzymes have the ability to convert them into nitrites which may be harmful."
Indeed, nitrates can be converted into two types of nitrites (nitric oxide or nitrosamines) which yield very different results. Nitric oxide is a good thing, but a conversion into nitrosamines is dicey.
Benefits of Nitrates
Although the word "nitrates" is often associated with meat, they're not the main source of the compound.
"The most common source of nitrates in the diet are leafy greens like spinach, beets and carrots," says anti-inflammation nutrition expert Dr. Barry Sears. Around 80 percent of the nitrates consumed by the average person comes from vegetables.
Nitrates found in vegetables are converted into beneficial nitrites when they come into contact with bacteria in the mouth. These help produce nitric oxide, which causes vasodilation (widening) of the arteries. This widening lowers blood pressure, allowing it to stay in a nice, normal range.
Nitrates are also added to processed meats as preservatives to prevent botulism, a potentially deadly form of food poisoning. And nitrates help to keep the meats looking pink rather than brown.
"Nitrite or nitrate salts (sodium nitrite, sodium nitrate, potassium nitrite and potassium nitrate) are used in most cured meat products, especially processed meats like ham, hot dogs, bacon, sausage, bologna, salami, smoked fish and cold cuts," says Danielle Gaffen, M.S., R.D.N. "When added to meat, the nitrite molecule chemically reacts with the meat to create nitric oxide, which is the agent responsible for curing the meat. Nitrate will not cure meat until it is converted to nitrite."
Drawbacks of Nitrates
Naturally occurring nitrates, such as those found in veggies, are believed to be safe, and even beneficial to consumers. "Studies have shown that naturally occurring nitrates may reduce the risk of cancer and reduce the risk of chronic health conditions," says Allison Gregg, R.D.N., L.D.N., a nutritional consultant at Mom Loves Best.
However, nitrates found in foods like cured meats, can turn into nitrites when combined with stomach acid, potentially forming carcinogenic nitrosamines. Also, "when protein and nitrates are cooked together at high temperatures, they can form nitrosamines that have carcinogenic [cancer-causing] potential," Sears notes.
Registered dietician Gaffen points out that once the concern became apparent, the acceptable nitrate levels used in processing were lowered. "Also because of this, vitamins C and E are now often added to cured meats to help reduce the nitrite reactions in the stomach," she says.
The good news is that the average person doesn't consume enough processed meats to do that much damage. The risk of bowel cancer is quite small. According to a 2019 article from the BBC, six out of 100 people in the U.K. will get bowel cancer at some point in their lives. For people who ate 50 grams of processed meat (three strips of bacon) every day, the chance moved to just seven out of 100.
"Of course, everything in moderation, I'd say that if your diet is generally unprocessed, produce-rich, full of healthy carbs, fats and proteins then the occasional charcuterie or bacon breakfast won't make or break your health," says Dr. Chris Airey, medical director at U.K.-based Optimale. "Remember, it is what we do on a daily basis consistently rather than single meals or workouts that contribute the most to our overall health."
Still, there are ways to avoid potentially damaging nitrates in food, if you prefer to play it totally safe. "Explore organic food options. Synthetic nitrates and nitrites are not permitted as preservatives in organic packaged foods and meats," says Gregg.